Structural and Functional Change in Albino Rat Retina Induced by Various Visible Light Wavelengths

The effects of visible light, from short to long wavelengths, on the retina were investigated functionally and histologically. The left eyes of Sprague–Dawley albino rats (6-weeks old, n = 6 for each wavelength) were exposed to seven narrow-band wavelengths (central wavelengths, 421, 441, 459, 501, 541, 581, and 615 nm) with bandwidths of 16 to 29 nm (half bandwidth, ±8–14.5 nm) using a xenon lamp source with bandpass filters at the retinal radiant exposures of 340 and 680 J/cm2. The right unexposed eyes served as controls. Seven days after exposure, flash electroretinograms (ERGs) were recorded, and the outer nuclear layer (ONL) thickness was measured. Compared to the unexposed eyes, significant reductions in the a- and b-wave ERG amplitudes were seen in eyes exposed to 460-nm or shorter wavelengths of light. The ONL thickness near the optic nerve head also tended to decrease with exposure to shorter wavelengths. The decreased ERG amplitudes and ONL thicknesses were most prominent in eyes exposed to 420-nm light at both radiant exposures. When the wavelengths were the same, the higher the amount of radiant exposure and the stronger the damage. Compared to the unexposed eyes, the a- and b-waves did not decrease significantly in eyes exposed to 500-nm or longer wavelength light. The results indicate that the retinal damage induced by visible light observed in albino rats depends on the wavelength and energy level of the exposed light.

Optical Model of Thermal Radiation Loading System for Turbine Vane Leading Edge

With the increase of combustion temperatures, the thermal radiation effect for hot components in the new generation of aero-engines has become a key factor in the combustion process, cooling structure design, and thermal protection. A radiation loading system can be used as an external heat source to simulate the real thermal environment of hot components in aero-engines. Total receiving power, as well as 3-D heat flux distribution, should better coincide with real conditions. With the aid of freeform optics and the feedback optimization method, the current study develops a concentrating-type radiation heating system fit for the leading-edge surface of a C3X turbine vane. A xenon lamp combined with a freeform reflector was optimized for controllable heat flux. A design method in the area of illumination engineering was innovatively extended for the current model. Considering the effect of polar angular radiative flux distribution of a xenon lamp, a Monte Carlo ray tracing (MCRT) method was adopted to evaluate the optical performance. Feedback modifications based on Bayesian theory were adopted to obtain the optimal shape of the FFS for target heat flux. The current study seeks a feasible way to generate 3-D heat flux distribution for complex curved surfaces, such as turbine vane surfaces, and helps to simulate the real thermal environment of hot components in aero-engines.

Plasmon-Modulated Excitation-Dependent Fluorescence and Antimicrobial Activities of Silver and Gold Nanoparticles Prepared with Eugenia unifloraL. extracts

Green synthesis using plant extract is a sustainable method to obtain silver and gold nanoparticles (Ag and AuNPs) and was employed in this work. The Eugenia uniflora L. fruits and leaves extracts were used in nanoparticles synthesis. The photoreduction process with a xenon lamp and pH control improved optical properties and nanoparticles stability. The UV-vis, TEM, FTIR, and Zeta potential of the prepared solutions were obtained. The fluorescence spectra of Ag and AuNPs were investigated at different excitation wavelengths, which showed two kinds of fluorescence peaks. The shorter wavelength peaks red-shift with the increasing excitation wavelength, which results from the electron interband transitions, and the longer fixed wavelength peaks due to the local field enhancement. Finally, the antimicrobial tests were performed with Gram-negative and Gram-positive bacteria and Candida albicans. The best results were obtained with EuAgNPs prepared with fruits extract, photoreduction, and pH 7.0 (with a mean of 95.12% ± 10.29% of inhibition).

Degradation of bacteria mass spectral signals via hydrothermal processing and UV irradiation: relevance to life detection on icy moons

<p>The inferred subsurface oceans of the icy moons of Jupiter and Saturn, in particular Europa and Enceladus, may contain conditions suitable for life. Plumes of material have been detected from Enceladus and may also be present on Europa. These plumes could contain molecular signs of habitability that could be detected by mass spectrometers on orbiting spacecrafts, such as the upcoming Europa Clipper mission. However, these molecular markers may have degraded between their production and detection, for example by possible hydrothermalism in the subsurface ocean or by UV irradiation once carried into space by the plume. It is important to look at how the biosignatures degrade under different conditions as degradation processes need to be taken into account when analysing the data from life detection missions. We investigate how these two processes affect the mass spectral signals of terrestrial bacteria.</p> <p>Two cyanobacteria samples, <em>Spirulina</em> and <em>Chlorella</em>, were subjected to hydrothermal processing and UV irradiation. Hydrous pyrolysis was used to simulate hydrothermal degradation. Experiments were carried out for 24 or 72 hours at temperatures between 200 and 300 °C. The pyrolyzed contents were subsequently extracted and analysed with gas chromatography-mass spectrometry (GC-MS). UV irradiation was carried out in a vacuum chamber (10<sup>-2</sup> mbar), using a 300 W short arc xenon lamp at UV to near infrared wavelengths (~250 – 800 nm). After UV irradiation, samples were analysed using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).</p> <p>Our results show that hydrothermal processing of cyanobacteria affects the compound classes in different ways. Carbohydrate and protein components from the cyanobacteria were significantly affected, with phenol and indole derivatives detected. However, some of the biological fingerprint, such as straight-chain even numbered saturated fatty acids from lipid fragments, remain even at the harshest experimental conditions used in our study. This provides confidence that these diagnostic molecules could be used as fingerprints of biological materials on icy moons.</p>

Invisible and Flexible Printed Sensors Based on ITO Nanoparticle Ink for Security Applications

Here, we propose a method to create a transparent security system based on printed conductive indium tin oxide (ITO)—the most widely used transparent conducting oxide material integrated into the devices with high transparency. Commonly used solution-processed ITO annealing methods are utilizing temperatures which are limiting the use of flexible polymeric substrates. Our method combines inkjet printing on flexible temperature-stable colorless polyimide (CPI) substrate with fast flash lamp annealing (FLA). In this study, millisecond pulses of visible light from a xenon lamp induce rapid heating of the ITO films up to 650°C through the light-absorbing additional layer of a colored organic dye onto printed ITO, whereas the CPI bulk never exceeds the melting point. Fabricated flexible ITO patterns on CPI film processed with the flash lamp annealing through the dye layer exhibit a transmittance of up to 85% at the wavelength of 550 nm and sheet resistance of 520 Ω/sq for a 70 nm layer thickness. With the proposed technology of our demonstrator realization—transparent glass/window or any other object such as a curved door lock can be used for integrating a touch-enabled transparent security access system, which would be completely invisible.

Synthesis and Characterization of Heterostructure Pd/Bi2WO6 Nanocomposites with Enhanced Properties of Visible-Light-Driven Photocatalyst

Heterostructure Pd/Bi2WO6 nanocomposites were successful synthesized in ethylene glycol by microwave-assisted deposition method at 300 W for 10 min. Effect of the loaded Pd on phase, composition, morphology and visible-light-driven photocatalytic properties of Bi2WO6 was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fast-Fourier-Transform (FFT) diffraction, UV-visible absorption and X-ray photoelectron spectroscopy (XPS). In this research, good distribution of cubic phase of spherical Pd nanoparticles with particle size of 15–20 nm supported on orthorhombic Bi2WO6 thin nanoplates. The 10% Pd/Bi2WO6 nanocomposites reveal major metallic Pd0 species containing in Bi2WO6 sample. Microwave can be used to synthesize metallic Pd nanoparticles supporting on top of Bi2WO6 nanoplates. Photocatalytic activities of Bi2WO6 loaded with different weight contents of Pd were monitored through photodegradation of cationic rhodamine B (RhB) dye under visible light irradiation of a xenon lamp. The 10% Pd/Bi2WO6 nanocomposites have the highest photocatalytic activity because Pd nanoparticles as electron acceptors promote interfacial charge-transfer through Pd/Bi2WO6 heterojunction.

Research of the polyethylene packaging layer structure change in contact with a food product at exposure to ultraviolet radiation

The sanitary and hygienic safety of modern packaging is determined by the layer of packaging material in direct contact with the food product. This layer in most cases is a synthetic polymer of the polyolefin class — low density polyethylene. This material is used as a stand-alone packaging and in multilayer and combined packaging materials. During thermal and photooxidation, compounds can form in it that negatively affect the safety of the package, which can migrate into the product. Food technologies use methods of disinfecting packaging materials and packaging before filling or bottling products. These methods include ultraviolet irradiation of the surface, which has a bactericidal effect. Using spectral methods of analysis, researches have been carried out on changes in the polyethylene layers structure in the film’s composition, multilayer films and combined packaging materials when exposed to pulsed ultraviolet radiation in a wide spectral range (irradiation with a pulsed xenon lamp). Deformations of polyethylene macromolecules chemical bonds on the surface and boundary layers under the influence of pulsed UV-irradiation have been revealed. The IR spectra of ATR (Attenuated Total Reflection) were obtained, the analysis of which showed that the monofilm is subject to the greatest destructive effect, as evidenced by the appearance of characteristic absorption bands responsible for the formation of aldehyde, ketone groups, as well as for the polymer chain termination. It is shown that the use of food soot in the composition of multilayer packaging films blocks their photo destruction. Upon irradiation of a combined material based on cardboard intended for bottling milk, an absorption band was found in the spectra, which is responsible for the onset of the destruction process with the formation of aldehyde and carboxylate groups with the formation of aldehyde and carboxylate groups.Comparison of changes in structure in three different packaging objects containing a polyethylene layer shows the feasibility and necessity of using combined and multilayer materials for food products packaging, in which, even under extreme UV-irradiation, there are practically no photo destruction processes, which is confirmed by spectral researches.

STUDYING THE INFLUENCE OF HIGH-INTENSITY PULSE OPTICAL UV RADIATION OF A XENON LAMP ON PURE CULTURES OF MICROORGANISMS

Проблема и цель. Целью данного исследования послужило теоретическое и практическое обоснование влияния высокоинтенсивного импульсного оптического УФ-излучения ксеноновой лампы на чистые культуры микроорганизмов – Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Proteus vulgaris, Klebsiella pneumonia, Hafnia alvei, а также изучение их чувствительности. Методология. Для достижения поставленной цели было проведено исследование с применением импульсной ксеноновой лампы прибора «Заря-1», основанное на использовании высокоинтенсивного импульсного оптического излучения сплошного спектра, генерируемого мощными высокотемпературными плазменными источниками. Проведены исследования бактерицидного действия различного количества импульсов излучения ксеноновой лампы на чистые культуры микроорганизмов. Эффективность воздействия УФ-излучения ксеноновой лампы оценивали путем подсчета количества выросших колоний микроорганизмов на агаризированных питательных средах в опытных и контрольных чашках Петри через 24 часа после их облучения и последующего выдерживания в термостате при температуре t=37 °C. Проведены анализы и сравнение полученного бактерицидного эффекта, обусловленного действием излучения с различными по количеству импульсами, в отношении изучаемых микроорганизмов, причем каждая из культур обладает неодинаковой чувствительностью к ультрафиолетовому излучению. Результаты. По результатам проведенной работы выявлена бактерицидная эффективность одного из вариантов излучения, что определяет исследуемый метод физической дезинфекции, как высоко результативный, опережающий по безопасности и эффективности химический метод и имеющий большие перспективы использования в животноводстве с целью обеззараживания воздуха животноводческих помещений. Заключение. Полученные результаты делают необходимым определение бактерицидного действия УФ-излучения импульсной ксеноновой лампы в отношении других видов микроорганизмов. Problem and purpose. The purpose of this study was the theoretical and practical substantiation of the efect of high-intensity pulsed optical UV radiation of a xenon lamp on pure cultures of microorganisms - Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Proteus vulgaris, Klebsiella pneumonia, Hafnia alvei, as well as the study of their sensitivity. Methodology. To achieve this purpose, a study was carried out using a pulsed xenon lamp of Zarya-1 device, based on the use of high-intensity pulsed optical radiation of a continuous spectrum, generated by powerful high-temperature plasma sources. There were studies of the bactericidal action of various numbers of xenon lamp radiation pulses on pure cultures of microorganisms. The efectiveness of exposure to UV radiation from a xenon lamp was assessed by counting the number of grown colonies of microorganisms on agar nutrient media in experimental and control Petri dishes 24 hours after their irradiation and subsequent incubation in a thermostat at a temperature of 37° C. Analyzes and comparisons of the obtained bactericidal efect caused by the action of radiation with pulses of diferent number in relation to the studied microorganisms were carried out. Each of the cultures had an unequal sensitivity to ultraviolet radiation. Results. Based on the results of the work carried out, the bactericidal efectiveness of one of the radiation options was revealed, which determines the studied method of physical disinfection as a highly efective chemical method that is ahead in safety and efciency, and has great prospects for animal husbandry when disinfecting the air of livestock buildings. Conclusion. The results obtained make it necessary to determine the bactericidal efect of UV radiation from a pulsed xenon lamp in relation to other types of microorganisms.